Closure assemblies for closing connecting links of tyre chains as well as connecting links for connecting at least two links of tyre chains are known from the prior art. In the known closure assemblies the connecting link is provided with a kind of shoe as a closure element. The shoe defines between two jaws, which are formed at the respective ends thereof, a leg reception member for receiving therein a normally flattened end portion of the leg of the connecting link. The jaws of the leg reception member of the shoe as well as the flattened ends of the connecting link are provided with holes for receiving therein pins or bolts. In most cases, one end of the connecting link is permanently held through a connection pin in a leg reception member of the shoe in a pivotable manner. For closing the connecting link, the shoe is pivoted to its closed position where the holes in the jaws of its leg reception member are in alignment with the hole in the end of the leg. Subsequently, a clamping pin is driven into the aligned holes of the leg reception member and the leg end by means of a hammer.
The closure assemblies and connecting links known from the prior art are problematic when the clamping pin is hammered in, insofar as the tyre to be provided with the tyre chain does itself not offer any suitable base for supporting the connecting link so as to adequately take up the forces occurring during hammering. This may have the effect that the connecting link, after having been hit by a blow, may spring back from the tyre and assume a position that is unsuitable for the next blow. Closing the connecting link may thus be rendered more difficult and time consuming, and the clamping pin may get damaged if hit unfavorably by the hammer. Although a tyre iron may be placed below the connecting link or annular lock during hammering so as to provide a firm base for supporting the connecting link or annular lock on the tyre, however, his course of action is troublesome and unable to prevent a displacement of the connecting link during hammering and, moreover, it normally requires at least four hands.
Problems in addition to those arising during closing of the connecting link may arise during opening of the connecting link, which necessitates a removal of the clamping pin from the holes in the leg reception member and the leg end. On the one hand, removing the clamping pin may be rendered difficult by the fact that the clamping pin has been jammed-in or deformed due to mechanical loads and that, consequently, very high push-out forces have to be applied, which, due to the above-mentioned insufficient support of the connecting link, are hard to apply. On the other hand, the clamping pin and/or the hole accommodating said pin may be corroded. This corrosion may primarily have the effect that the pin gets stuck in the hole, whereby the forces required for knocking the pin out will be further increased. In addition, the pin may be weakened through corrosion such that it gets deformed during knocking out, whereby such knocking out will be rendered still more difficult or even impossible.
If it should no longer be possible to knock out the pin, the connecting link will have to be cut open, e.g. by means of a cutting torch. Cutting the connecting link open by means of a cutting torch will, however, entail the risk of causing damage to the tyre through the resultant heat. Such cutting open can therefore only be regarded as an emergency measure, if all the other efforts to open the connecting link by removing the pin should have failed.